For many years, various types of protective covers formed from paper have been available for covering books and especially books having stiff covers. However, paperback books have increasingly come into use because of their lower cost as compared to hard cover books. One problem with paperback books is that the covers thereof are easily bent, frayed or otherwise mutilated, rendering the book unsightly. While it is desirable to have protective covers for paperback books, magazines, technical journals and the like which prevent the covers thereof from becoming worn, bent, frayed or otherwise mutilated, no cover has been made available which is adjustable to accommodate books of varying thicknesses which is easy to manipulate and is not unsightly or ungainly to use.
To apply a certain specific size protective book cover respectfully to a relatively thin book and also to a relatively thick book of the same size usually results in the protective cover being much too large for the thin book so that a very loose fitting results and the desired support and protection is not realized, while if the same cover is applied to a relatively thick book and particularly one which is too thick to actually be accommodated by such protective cover, damage will be sustained by the book after a relatively short period of time with the spine of the book covers becoming broken as well as other forms of disfigurement.
Various attempts have been made to provide adjustable book covers, but none has resulted in a completely satisfactory book cover, particularly for use with the so called paperback books. Representative efforts in this field are the disclosures of the Birchard et al. U.S. Pat. No. 307,004; the Tilley U.S. Pat. No. 540,469; the Nourse U.S. Pat. No. 770,692; the Bull U.S. Pat. No. 1,472.789; the Ayers et al. U.S. Pat. No. 3,002,768; and the Learned et al. U.S. Pat. No. 3,572,767. While all of these patents to some degree or another show a protective cover for a book, magazine or pamphlet, and in some cases the covers are adjustable, none of the patents provide an automatically ajdustable protective cover of the type hereinafter set forth.